Metal bending apparatus



Jan. 10, 1939. H. w; JESPERSEN I METAL BENDING APPARATUS HIIIII" 1 Filed March ll, 1936 IlHIIIHIHHIIIIIHI Flai? z?A Patented Jan. 10, 1939 METAL BENDING` APPARATUS Helge W. `Iespersen, Western Springs, Ill., assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application March 11,

6 Claims.

This invention relates to metal bending apparatus, and more particularly to apparatus for bending metal rod.

An object of the invention is to provide simple and inexpensive apparatus for easily and quickly bending metal rod and the like.

Apparatus embodying the present invention -is particularly useful for producing bends of small radii compared to the thickness or diameter of the rod. i

In accordance with one embodiment of the invention, there is provided a rod bending apparatus comprising means for holding a portion of a rod, and a lever for engaging another portion of the rod, the lever having eccentrically mounted thereon an arcuate forming member or mandrel about which the rod is wrapped upon actuation of the lever.

Other features and advantages of the invention will become apparent from the following detailed description when read in conjunction with the accompanying drawing, in which- Fig. 1 is a fragmentary plan view of a metal rod bending apparatus embodying the features of the invention, the bending lever being shown in its initial or starting position;

Fig. 2 is a fragmentary longitudinal section one line 2 2 of Fig. 1;

Fig. 3 is a fragmentary transverse section on line 3-3 of Fig. 1, and

Figs. 4 and 5 are fragmentary plan views similar to Fig. 1, but showing the bending lever in its intermediate and final positions, respectively, when forming a U-bend in a rod.

The invention is illustrated in the drawing as embodied in an apparatus for forming from nichroine wire or rod, electrical heating elements of serpentine form in which the radii of the regular reverse bends are small compared to the 40 diameter of the rod. Referring to the drawing,

. the apparatus comprises a supporting plate or table I9 having a block II (Fig. 2) secured to its under side near one end thereof. The block I! has a rectangular cavity I2 and the plate I9 has a rectangular slot I3 directly above the cavity I2. The slot I3 is of the same length as the cavity but of lesser width so that the slot and cavity together form a dove-tail slideway for a slide I4.

A hand lever I5 is fulcrumed in the slide I4 so that it is pivotally movable in a horizontal plane above the plate I9. A forming block I6 is removably secured upon the lever I5, as by means of screws Il. The forming block is formed with upstanding portions I8 and I9 which are spaced apart to provide a groove or channel adapted to 1936, Serial N0. 68,260

receive a rod 29 to be bent. The portion I8 of the forming block is disposed eccentrically with respect to the pivotal axis of the lever and its end nearest the pivotal axis is rounded, as shown at 24, to serve as a mandrel about which the rod is wrapped when the apparatus is operated, as hereinafter described. The center line of the rounded end or mandrel portion 24 of the forming block is spaced from the pivotal axis of the lever I5 by a distance determined by the diameter of the rod to be bent and the radius. of the bend to be produced. This distance S may be computed by the formula wherein d is the diameter of the rod and r is the radius of the bend to be produced.

Removably secured on the plate III` is a holding block 25 having upstanding ribs 26 and 21 which are spaced apart to provide a channel adapted to receive the rod being bent. The ribs 26 and 27 are at right angles to the direction of movement of slide I4, and the rib 2li, which is nearest the pivotal axis of lever I5, is in line with the upstanding portion I9 of forming block I6 when the lever is in its initial or starting position shown in Fig. 1. A ller plate or plank 29 is attached to the top surface of table plate I0 in front of holding block 25 to receive and support the initially bent portion of the rod. The top surface of the plank 29 is ush with the bottom of the channels in forming block I6 and holding block 25.

`The ribs 29 and ZIcorrespond in thickness to the radii of the bends to be produced. Both ends of rib 2l and the outer end of rib 26 are rounded, as shown, to fit the bends formed in the rod.

The holding block 25 is undercut at its corner nearest the pivotal axis of lever I5 so that the lever is free to swing and slide thereunder but is restrained against vertical movement.

in operating the apparatus to form, for eX- ample, a serpentine shaped electrical heating element from a nichrome rod 2G, the hand lever I5 is initially positioned as shown in Fig. 1,'the slide I4 being in its rearmost position. The rod 2U is then positioned in the apparatus so that the portions of the rod, between which the iirst bend is to be made, are disposed in the channel of the forming block I6 and along the outer side of the holding rib 26, respectively. The hand lever I5 is then turned in a clockwise direction through 180 to the position shown in Fig. 5, whereby the rod is wrapped about the mandrel portion 24 of the forming block to form the first U-bend. As the lever is moved from the starting position to the intermediate position shown in Fig. 4, the slide I4 in which the lever is fulcrumed is moved forwardly, and during the last half oi the pivotal movement of the lever, the slide returns to its original rearmost position. This movement of the slide compensates for the eccentriclty of the mandrel portion 24 with respect to the pivotal axis of the lever so that the axis or center line of the mandrel portion is constantly maintained in the same vertical plane throughout the bending operation.

Upon the completion of the first U-bend, the rod is removed and the lever l is returned to its starting position., The rod is then repositioned in the apparatus so that the U-bend just formed engages the rounded end of the holding rib 26 with the short end of the rod lying between the holding ribs 2G and 2l and the long end of the rod lying along the outer side of holding rib 26 and in the channel of the forming block IG. The lever is then operated to form the second U-bend in the same manner in which the rst U-bend was formed, after which the rod is removed and the lever is again returned to starting position. The rod is then inverted and repositioned in the apparatus so that the last formed bend engages the rounded end of holding rib 26 and the rst formed bend engages the opposite end of holding rib 2'! with the portion of the rod between the bends lying between the hold-- ing ribs and the longer end of the rod lying along the outer side of holding rib 25 and in the channel of the forming block l5. The lever is then operated to form the third U-bend and the above procedure is repeated to the completion of last U- bend, the rod being repositioned after each U- bend is formed so that the last formed U-bend engages the rounded end of the holding rib with the remaining unbent portion of the rod lying along the outer side of holding rib 2E and within the channel of the forming block I5.

The forming block i6 and the holding block 25 may quickly be removed and replaced by other forming and holding blocks adapted to, bend rods of different diameter or produce bends of different radii. Y

It should be understood that the invention is not limited to the specific embodiment thereof herein illustrated and described except insofar as is defined by the appended claims.

What is claimed is:

l. In an apparatus for bending metal rod, a support, a slide mounted in the support, means on the support for positioning and holding a rod so that its longitudinal axis is substantially at right angles to the direction of movement of the slide, a lever fulcrumed in the slide, and a forming rmember eccentrically mounted on the lever about which the rod is wrapped upon actuation of the lever.

2. In an apparatus for bending metal rod, a support for holding a rod to be bent, a lever having a slidable pivot in the support, means on the supportV for positioning and holding the rod so that its longitudinal axis is substantially at right angles to the direction of movement of said pivot, and a forming member mounted on the lever and about which the rod is wrapped by rotating of the lever about said pivot and simultaneously moving said pivot.

3. In an apparatus for bending metal rod, a support for holding a portion of a rod, and a lever fulcrumed in the support for engaging another portion of the rod, the lever having a forming member eccentrically mounted thereon about which the rod is wrapped upon actuation of the lever, the center of said forming member being spaced from the pivotal axis of the lever by a distance substantially equal to one-fourth of the circumference of a circle whose diameter is equal to the diameter of the rod plus twice the radius of the bend to be produced.

4. In an apparatus for bending metal rod, a

support, means fixed on said support for holding a portion of a rod to be bent, a lever fulcrumed in the support, and means fixed on the lever for holding another portion of the rod, said means comprising an eccentric forming member about which the rod is wrapped upon actuation of the lever, the center of said forming member being spaced from the pivotal axis of the lever by a distance substantially equal to one fourth the circumference of a circle whose diameter is equal to the diameter of the rod plus twice the radius l wherein S is the distance between the center of the mandrel and the pivotal axis of the lever, d is the diameter of the rod and r is the radius of the bend to be produced.

6. In a bending tool, a mandrel having a curved surface for forming the inside of a bend in a rod or the like, and a means for holding the rod or the like against movement at a point distant from the bend being made, said mandrel being pivotally mounted on a pivot point outside of said curved surface, said pivot point being spaced from the center of said curved surface by a distance substantially equal to one-fourth the circumference of a circle whose diameter is equal to the diameter of the rod or the like being bent plus twice theV radius of the bend to be produced so that when the mandrel is swung about the pivot to perform the bending operation, there is substantially a minimum of slippage of the latter on the curved surface.

- HELGO W. JESPERSEN. 

